1. Field
The present disclosure relates to microfluidic apparatuses for inducing a flow of a fluid according to a centrifugal force, and separating and recovering a target material from a sample in a fluid form.
2. Description of the Related Art
Most malignant tumor-related deaths are caused by metastasis to a tissue or organ located away from a point where a tumor originated. Thus, the discovery of metastasis at an early stage is a critical factor that determines the survival probability of a cancer patient. Early detection and monitoring a growth of a tumor are deemed to be key factors in successfully treating cancer patients. A histopathology-based diagnosis is usually used to detect a cancer. The histopathology-based diagnosis is a method of diagnosing a tumor by using a tissue sample obtained from a biopsy specimen. According to the histopathology-based diagnosis, a tumor cell is directly observed. However, a biopsy specimen only provides information about the tissue contained in the biopsy specimen, and thus, a biopsy specimen may not generally be used to identify tumor metastasis. Accordingly, the use of histopathology in diagnosing or monitoring tumors, especially metastasized tumors, has many limitations
Circulating tumor cells (CTCs) may be identified in patients before a tumor is originally detected. Thus, CTCs may play an important factor in early diagnosing of a cancer. In addition, since a cancer may spread through blood, CTCs may be considered as a marker for identifying cancer metastasis. In addition, when CTCs are detected after a tumor is removed by a surgical operation, the possibility of recurrence of a cancer is very high. However, since the amount of CTCs in blood may be very small and since CTCs are very fragile, it is difficult to correctly quantify CTCs. Accordingly, there is a need to develop a diagnosis method having high sensitivity in detecting CTCs, cancer cells, or cancer stem cells present in the body of patients.
Red blood cells, white blood cells/circulating cancer cells, or serums may be manually separated based on a density gradient of a layer in order to isolate CTCs, cancer cells, or cancer stem cells. However, a layer of white blood cells/circulating cancer cells is very thin, and thus, manually separating the layer of white blood cells/circulating cancer cells based on the density gradient is difficult, and also, the separation reproducibility largely depends on the ability of a person who performs the separation.